ES2822137T3 - Automated work platform assembly - Google Patents

Abstract

An automated work platform assembly (30) for remotely servicing a lower portion of a vessel (12), the platform assembly comprising: a generally horizontal circular work platform (32) extending in the foreground; an orbital trace (34) extending in a second plane substantially parallel to the first plane and in which the work platform (32) is rotatably supported to rotate the work platform in the foreground, the orbital trace including a ring circumferential drive mechanism (54) incorporating gear teeth (56); a planetary gear structured to interact with the gear teeth of the circumferential drive ring (54); a remotely controlled motor (60) for rotating the work platform (32) on the orbital path (34) by driving the planetary gear; a linear trace (68) extending across a diameter of the work platform (32); a carriage (64) that can travel remotely on the linear path (68) through the diameter of the work platform (32); and a robot (74) fixed to and movable with the carriage (64), the robot presenting a vertically extending member which can be movable in a direction perpendicular to the first plane and which has a receptacle near a distal end of the vertically extending member to support a tool.

Description

DESCRIPTION

Automated work platform assembly

Background

1. Field

The present invention relates generally to the maintenance of components below the vessel of a nuclear reactor and, more specifically, to an automated high speed work platform below the vessel for servicing drive mechanisms of control rods and other components below the vessel of a boiling water reactor.

2. Related art

Control rod pull mechanisms are used to position the control rods of boiling water reactors to control fission rate and fission density, and to provide sufficient excess negative reactivity to shut down the reactor as a result. from any normal or accidental operating situation at the most reactive time in the life of the core. Figure 1 is a sectional view of a boiling water nuclear reactor pressure vessel 10 with portions cut away to expose the interior illustrating the environment in which a control rod drive mechanism operates. The reactor pressure vessel 10 has a generally cylindrical shape and is closed at one end by a fixed bottom head 12 and at its other end by a removable head 14. A side wall 16 extends from the bottom head 12 to the upper head 14. A cylindrical shaped core shield 20 surrounds a reactor core 22. Shield 20 is supported at one end by shield bracket 24 and includes a removable shield head at the other end. A crown 28 is formed between the shield 20 and the side wall of the vessel 16.

Heat is generated within core 22, which includes fuel bundles 36 of fissile material. Water that is circulated upward through core 22 is at least partially converted to steam. Steam separators 38 separate the steam from the water, which is put back into circulation. The residual water is removed from the steam by steam dryers 40. The steam exits the pressure vessel 10 through a steam outlet 42 near the upper vessel head 14 and is generally used to drive a turbo generator for production Of electricity.

The fuel bundles 36 are aligned by a lower core plate 50 located at the base of the core 22. An upper guide 52 aligns the fuel bundles 36 as they are lowered into the core 22. A core plate 50 and an upper guide 52 are supported by core shield 20.

The amount of heat generated in the core 22 is regulated by inserting and removing the control rods 44 of neutron absorbing material, for example hafnium The control rods extend from the bottom of the vessel to the interior of the core . Up to the point where the control rods 44 are inserted between the fuel bundles 36, the control rods absorb neutrons that would otherwise be available to facilitate the chain reaction that would generate heat in the core 22. Control guide tubes 46 from the control rods below the lower core plate 50, align the vertical movement of the control rods 44 during insertion and removal. Hydraulic control rod drivers 48, extending through bottom head 12, perform insertion and removal of control rods 44. Each control rod driver is vertically mounted in a control rod drive housing 18 which is welded to a stud tube, which, in turn, is welded to the bottom head of the reactor vessel 12. A flange of the drive mechanism The control rods is bolted and sealed to the control rod drive housing flange 18, which contains holes to secure the hydraulic system lines of the control rod drive mechanism. The demineralized water supplied by the control rod pulling mechanism hydraulics serves as a hydraulic mechanism to activate the operation of the control rod pulling mechanism.

Document US 4292133 discloses an apparatus for replacing the drive mechanisms of the control rods of nuclear reactors and includes a device for fixing and releasing the drive mechanisms of the control rods and a device for handling the drive mechanisms of the control rods mounted on a rotating device so that they can be moved independently of the other. The rotating device is mounted in a space below the pressure vessel of the nuclear reactor.

JP S 4346595 A discloses a device for changing a control rod drive mechanism arranged in the lower portion of a nuclear reactor.

The drive mechanisms of the control forms are frequently removed from the reactor for revision in order to maintain their reliability. All boiling water reactors use the same under-vessel platform that was installed during construction for checking the control rods. Existing platforms are slow and can only be controlled by a technician from below the vessel at the same time uses on the platform a manual control that communicates with an air motor or an electric ac motor. The only alternative is a manually operated steering wheel. In addition to being slow, existing work platforms require sub-vessel technicians to disregard assigned tasks in order to properly position a platform, often causing mounting below the wrong location. Due to this situation, and the operational process of existing work platforms, many errors, saved situations in extremis, and equipment damage occur during planned system outages. Accordingly, a new working environment below the vessel is desired that facilitates remote operation, new service techniques, and a more efficient service operating environment.

Summary

These and other objectives are achieved by an automated work platform assembly for remote inspection of a lower portion of the vessel according to claim 1. The platform assembly includes a generally horizontal work platform extending into a first plane and a generally circular rail extending in a second plane, substantially parallel to the first plane, the rail supporting an orbital path on which the work platform is rotationally supported to rotate the work platform in the first plane. A remotely controlled motor rotates the work platform on the orbital path and a linear path runs down one side of the diameter of the work platform. A carriage can be remotely moved along the linear path from one side of the diameter of the work platform to the other. A robot is attached to the cart and can move with it. The robot has a vertically extending member movable in a direction perpendicular to the first plane and has a socket near a distal end of the vertically extending member to support a tool. Preferably, the automated work platform assembly includes a steering wheel for manually moving the work platform around the orbital path as an alternative to the remotely controlled motor. In one embodiment, the robot is an interchangeable task robot and the work platform supports a generally focused camera on a distal end of the limb that extends vertically over the robot. Preferably the camera is configured to offer remote controlled panning capability.

In another embodiment, where the vessel is a nuclear reactor vessel incorporating a nuclear core, the remotely controlled motor for moving the work platform on the automated work platform assembly and the remotely controlled carriage are configured to communicate with a controller and respond to the reactor core coordinates input to the controller to move the horizontally extending member below a core position associated with the coordinates.

Preferably, the nuclear reactor vessel includes a refueling bridge configured to be positioned above the nuclear core and move from one or more pieces of the refueling equipment above the nuclear core towards coordinates directed between those introduced in a refueling system command station, in which the controller and the refueling system command station are automatically coordinated so that the refueling bridge and the controller do not direct the same coordinates at the same time.

Brief description of the drawings

A further understanding of the invention can be obtained from the subsequent description of the preferred embodiments taken in conjunction with the accompanying drawings, in which:

Figure 1 is a sectional view, with two parts cut away, of a pressure vessel of a nuclear reactor in boiling water;

Figure 2 is a perspective view of the nuclear reactor pressure vessel of Figure 1 with the working platform of the present invention installed below the reactor vessel;

Figure 3 is a perspective view of the work platform of the present invention;

Figure 4 is an enlarged view of the horizontal automated wagon illustrated in Figure 3; Figure 5 is a perspective view of the work platform shown in Figure 3 with an interchangeable task robot shown connected to the horizontal automated wagon;

Figure 6 is a perspective view of the underside of the work platform shown in Figure 3; Figure 7 is an enlarged view of a portion of Figure 6 showing the automated horizontal wagon towing mechanism on the linear trace and the precision positive captive wheel mounts mounted on the orbital trace;

Figure 8 is an enlarged view of a second portion of Figure 6 showing a clearer view of the rotary drive mechanism on the circumferential drive ring;

Figure 9 is a plan view of the work platform of the present invention with a schematic representation of the core locations under which the horizontal automated wagon can be programmed with respect to its location;

Figure 10 is a perspective view of the work platform of the present invention with an embodiment of the interchangeable task robot connected to the horizontal automated wagon adding third, fourth and fifth axes of displacement;

Figure 11 is a perspective view of the work platform shown in Figure 10 with a second embodiment of an optional interchangeable task robot that adds a third axis of displacement, with a fourth vertical rotary axis;

Figure 12 is a third embodiment of the automated platform of the present invention with an interchangeable task robot that adds a third and fourth axes of displacement; Y

Figure 13 is a perspective view of the reactor vessel shown in Figure 3, schematically showing two optional control procedures of the robotic platform of the invention.

Description of the preferred embodiment

The working platform below the automated high speed vessel of the present invention will be used to carry out remote maintenance and repair work of the vessel below the boiling water reactor, without the need for personnel below the vessel. The system will execute these work activities with greater precision, with greater accuracy and faster, as well as to offer a concurrent verification in the time of the activity by means of high definition cameras on board. The automated high-speed under-vessel work platform features three automated axes comprised of a 360 ° rotating horizontal axis, a linear horizontal axis through a traversing wagon (also referred to as a carriage), and a linear vertical axis through of interchangeable task robots that may also contain fourth and fifth axis capabilities. Interchangeable task robots can be fixed by staff or stored below the vessel and retrieved by the remotely operated horizontal wagon. Another advantage of the automated high-speed under-pot work platform is the ability to automatically navigate to a specific location simply by keying in the core location into control software. The automated high-speed under-vessel work platform has the ability to also be operated manually by a steering wheel and locally by means of a manual control. Task robots will carry out tasks such as inspection of locking steel structures, all visual inspections of any kind, application of labels, concurrent checks, removal of position indicating probes, uncoupling of mechanisms control rod pulling, detorsion of control rod trolleys, re-torsion of control rod trolleys and disconnection of monitors from the local power range, removal and control of the installation of the fuel channel drainage for supervision of the power range, as well as the change of the drive mechanisms of the control rods.

Figure 2 shows a perspective view of the reactor previously shown in Figure 1 with the working platform under vessel 30 supported below the control rod drive mechanisms 18. The working platform 30 can be better appreciated in the views. shown in Figures 3-8. The under-vessel work platform assembly 30 features an orbital tracing 34 attached circumferentially to under-vessel tracing mounting locations 35. Orbital tracing 34 features a circumferential drive ring 54 having gear teeth 56. The work platform 32 is fixed to the orbital path 34 by means of precision positive captive wheel supports 58 which can be optimally observed in Figures 7 and 8. The captive wheel supports they allow load transfers to the work platform 32 in any direction. The work platform 32 features an electrically powered rotary drive mechanism 60 comprising a planetary gear that interconnects with the gear teeth 56 of the circumferential drive ring 54 that allows rotation of the platform through 360 °. Work platform 32 features a linear tracing system 62 comprising a horizontal automated wagon as best seen in Figures 4 to 8. Horizontal automated wagon 64 features an electrically powered towing mechanism 66 comprising a planetary gear which interconnects with a toothed rack 68 horizontally mounted within the work platform 32. With the circumferential axis and the horizontal axis, the automated cart 64 can be remotely located at any location below the vessel. The horizontal automated wagon 64 features a remotely operated high definition camera 70 and spring loaded feed and position feedback pins 72. The pins 72 provide power to and feedback from 74 interchangeable automated task robots that are designed to be inserted into the horizontally automated cart 64 as illustrated in Figure 5. The automated task robots 74 perform a variety of work tasks on the components under the vessel as well as simple tasks such as hangtags, operating valves, and checks concurrent by means of visual observation through camera 70. As can be seen in Figure 13, the entire system can be logically operated by means of a hanger 76 at a contractor control point with a controller 84 or remotely by means of a from control room 78. Controller 84 communicates with the refueling system command station above the refueling floor 82 so that the refueling bridge and the work platform under the vessel 32 are each aware of the position of the other with respect to the core so that proper work processes can be adhered to. Preferably, the refueling floor 82 monitors the position of the cart 84 on the work platform 32 but has no control over the positioning of the cart. The control room 78 can control the cameras and monitor the position of the work platform 32. The controller 84 presents both a view of the camera feed as well as the complete control of the assembly of the work platform 30 and the hanger 76 can control the entire movement of the work platform assembly 30. As figuratively illustrated in Figure 9, by keying in a cell location within the software, the automated high-speed under-vessel work platform can automatically move to that cell site; eliminating the HuP (human benefit) trap of wrong-site work.

Figures 10, 11 and 12 show three different interchangeable task robots that can be used with the horizontal automated wagon 64. The robot 74 of Figure 10 has third, fourth and fifth axes of travel. Robot 74 illustrated in Figure 11 adds a third axis with a fourth vertical rotary axis. The robot 74 illustrated in Figure 12 adds a third and fourth axes. The axes of movement of the robots illustrated in Figures 10, 11 and 12 are shown figuratively by the directional arrows superimposed on those figures.

Accordingly, the under-pot work platform of the invention can be remotely operated and provide feedback to the operator about its exact location, while also providing continuous live video of the entire under-pot work area. The under-vessel work platform can provide remote human inspections and scans of the entire area under the vessel or through the control room or other control point without the need for assembly by personnel; The inspections could even take place during normal plant operation, a feature currently not available in any boiling water reactor installation. The work platform has the ability to communicate with the refueling bridge, identifying the work site of each of its operators. The work platform of the present invention can drastically cut the proposed under-vessel radiation dose expectations for plant shutdowns. The platform retains the capacity for manual handling by means of a steering wheel that can be inserted into the reference numeral 80 shown in Figure 5.

Although specific embodiments of the invention have been described in detail, it should be appreciated by those skilled in the art that various modifications and alternatives to those details may be developed in light of the overall teachings of the disclosure. Accordingly, the specific embodiments disclosed are intended to be only illustrative and not limiting of the scope of the invention, scope to which the full breadth of the appended claims should be granted.

Claims (11)

1. - An automated work platform assembly (30) to remotely service a lower portion of a vessel (12), the platform assembly comprising: a generally horizontal circular work platform (32) extending in the foreground; an orbital trace (34) extending in a second plane substantially parallel to the first plane and in which the work platform (32) is rotatably supported to rotate the work platform in the foreground, the orbital trace including a ring circumferential drive mechanism (54) incorporating gear teeth (56); a planetary gear structured to interact with the gear teeth of the circumferential drive ring (54); a remotely controlled motor (60) for rotating the work platform (32) on the orbital path (34) by driving the planetary gear; a linear trace (68) extending across a diameter of the work platform (32); a carriage (64) that can travel remotely on the linear path (68) through the diameter of the work platform (32); Y a robot (74) fixed to and movable with the carriage (64), the robot presenting a vertically extending member that can be movable in a direction perpendicular to the first plane and having a receptacle near a distal end of the member that extends vertically to support a tool. 2. - The automated work platform assembly (30) of Claim 1, which includes a steering wheel (80) to manually move the work platform (32) around the orbital path (34). 3. - The automated work platform assembly (30) of Claim 1, in which the robot (74) is a robot with interchangeable tasks. 4. - The automated work platform assembly (30) of Claim 1, wherein the work platform (32) supports a camera (70) generally focused on the distal end of the vertically extending member. 5. - The automated work platform assembly (30) of Claim 4, wherein the camera (70) is configured to have a remote controlled panoramic capability. 6. - The automated work platform assembly (30) of Claim 4, wherein the camera (70) is configured to have remote controlled tilt capability. 7. - A nuclear reactor comprising: a nuclear reactor vessel (10); Y the automated work platform assembly (30) of any of claims 1 to 6. 8. - The nuclear reactor of claim 7, wherein the automated work platform assembly is sized to fit under the vessel (10). 9. - The nuclear reactor of claim 7, in which the nuclear reactor vessel has a nuclear core (22), a refueling system command station (82) to refuel the core and the remote controlled motor (80 ) to move the work platform (32) and the remotely controlled carriage (64) are configured to communicate with the controller (84) which is configured to control the movement of the remotely controlled motor to move the work platform and carriage remotely controlled and communicating with the fuel system command station, so that the fuel system controller and command station are each aware of each other's position so that proper work processes can be adhered to. The nuclear reactor of claim 9, wherein the controller (84) is configured to receive the coordinates of the reactor core (22) input into the controller to move the vertically extending member below a position of the nucleus associated with the coordinates. 11. - The nuclear reactor of claim 10, wherein the automated work platform assembly (30) includes a refueling bridge configured to be located above the nuclear core (22) and the refueling system command station It is operable to move one or more pieces of the refueling equipment on the nuclear core towards the directed coordinates between those entered in the refueling system command station, in which the controller (84) and the refueling system command station they are automatically coordinated so that the refueling bridge and the controller are each aware of each other's location.